The present invention is related to co-pending United States patent application Ser. No. 06/553,106 filed on the same date as the present application with two common inventors and a common assignee. Said application, incorporated herein by reference, relates to chemical bonded laminates generally, with condensation polymer laminae species. The present application relates to addition polymer species.
As with interfacially bonded laminates of oriented condensation polymer films, sheets or strips of oriented addition polymer films and the like suffer from deficiencies in bonding which have hampered exploitation of attractive properties. A generality pertaining to oriented films is that the greater the degree of orientation in one direction to impart high levels of mechanical properties, such as tensile strength, the lower the level of properties in the transverse direction. In uniaxially oriented film both tensile strength and elongation before break in the direction transverse to orientation can be so low that in ordinary processing or manipulation the film fibrillates, rendering it useless for some applications which could otherwise employ its high tensile strength.
High tensile strengths typical for in uniaxially oriented film are unattainable in biaxially oriented film; so attempts have been made to fabricate cross-lapped, interfacially bonded, laminar structures with the direction of orientation at an angle to each other in successive laminae or layers to thus capitalize on the very high tensile strength of uniaxial films. In the common methods of bonding, adhesives have been less than totally suitable and fusion bonding destroys or excessively diminishes orientation, defeating the purpose of orientation to produce a high level of mechanical properties.
The present invention is directed to a type of bonding minimizing some of these deficiencies.